It's not that Colin Kaepernick, who would take over for Alex Smith if he can't go this week against the Bears, is the most experienced or savvy of the three backups who could play. It's that he fits with what they do better -- and the 49ers are not a quarterback-centric team.

The Bears, who could play Jason Campbell over Jay Cutler because of Cutler's concussion, are Cutler-centric. His ability to throw ropes and make improvisational plays is what makes that team's offense go. Campbell can't do that.

In Pittsburgh, Ben Roethlisberger's ability to move away from pressure is what makes him special. Does any quarterback make more plays on the move with their arm than Roethlisberger? He won't with a banged-up shoulder and a broken rib, so the Steelers will have to adjust in a big way. Byron Leftwich is a big-armed passer, but he lacks foot speed and he has a long windup.

In studying the tapes from each of the three backups from last week's games, I saw a lot of interesting things. I expected to like the veterans more, but Kaepernick, after a slow start, did some really good things.

Here's a short look at each of them.

Breaking down Kaepernick

After coming into the game in the second quarter against the Rams, Kaepernick looked early on like an inexperienced quarterback. He rushed plays, got out of the pocket too quickly, and seemed hurried.

Here's a play that he made early that was called back for holding. It would have been a positive play if it stood up, but the reality is that it was a negative because he missed what would have been a touchdown.

As you can see by the first picture, the 49ers have two receivers to the right of Kaepernick with tight end Vernon Davis offset on the left inside of Randy Moss. Kyle Williams is in the slot on the right, and Mario Manningham is outside of him. At the snap, both players run go routes, and Rams safety Quintin Mikell breaks to the outside to double Manningham. That leaves Williams wide open in the middle, so wide open he puts his hand up for Kaepernick to see. But the quarterback never sees him. He instead escapes pressure -- a good move by him -- and completes the pass to running back Kendall Hunter for a 15-yard gain that is called back. It's a solid play by the quarterback, but one that should have been better -- if there weren't a hold in the backfield.

The good news is Kaepernick got better as the game moved along. He seemed to gain more confidence with each throw.

Here's a play where Kaepernick scrambles away from pressure, and with a lot of room in front of him, he holds off on running and fires a shot for a 13-yard gain to Williams. As you can see by the first picture, he has a ton of room to run. The second picture shows him with his head up, throwing the pass shot to Williams, who is wide open.

That's the growth I saw from him as the game went on, the kind of thing that makes me think he will be just fine if he has to play against the Bears. He did lose a fumble on a sack, and also fumbled a snap that was recovered by Frank Gore. Those things can't happen against the Bears. But he should be fine.

Breaking down Campbell

When I studied Campbell's play against the Texans, I had to take into account the weather conditions -- it was pouring -- and the fact he was playing one of the NFL's best defenses. The other thing that stood out was the primitive nature of the Bears' offensive philosophy in this game. It lacked creativity, but then again this is a team that runs one-man routes at times.

It appeared to me that Campbell was too Brandon Marshall-reliant. Yes, Marshall is having a huge year, but Campbell passed on bigger plays to try and get the ball to Marshall. That was obvious.

Here's an example of that. He has Marshall (yellow circle) lined up to his left outside of Earl Bennett (red circle). Marshall runs a short curl route, while Bennett runs a corner route. As you can see, Marshall is an easy target. But Campbell should wait for Bennett to clear, which Bennett does as you can see by the second and third pictures.

On the final play of the game, a fourth-down try with the Bears trying to tie the game, Campbell forces a ball to running back Matt Forte. He passes on a big-play chance to tight end Kyle Adams or a first-down throw to Marshall, who is open on the left sideline.

As you can see from the pictures below, the Texans have Forte (yellow circle) covered well. You can see Adams (blue circle) wide open and Marshall (red circle) settled in wide open on the left sideline. This is just a bad decision by Campbell.

If Campbell is to play this week and beyond, and the Bears are to have a chance to beat the 49ers, he has to take more shots. The safe throw isn't always the right throw.

Breaking down Leftwich

Leftwich isn't going to make anybody think he's the next coming of Roethlisberger, especially as it relates to mobility. But Leftwich is smart. If given time, he will find the open receiver.

That's what I saw from the tape of his second-half work against the Chiefs. He didn't do a lot of great things, but when given time, he made the plays. He did so by reading the field.

Here's an example. On a third-and-8 from his own 16, Leftwich takes the snap and looks to his right, where the Steelers have a bunch formation. It appears he wants to get the ball to tight end Heath Miller on the right side, but he's covered. So Leftwich steps up into the pocket and fires a shot to Emmanuel Sanders for a 31-yard catch-and-run.

The Steelers didn't try to take shots down the field when Leftwich came into the game. That has to change against the Ravens. He is a long-ball thrower, but, of course, that will take protection. He is a long strider with a big windup. That means he needs room to throw. If he doesn't have it, mistakes will be made. Expect the Ravens to come after him.

Film study

1. When Kevin Gilbride said that 49ers defensive end Justin Smith was one of the best in the NFL at holding, he was right. 49ers coach Jim Harbaugh might not like the accusations, but they are accurate. Justin Smith is a big reason why Aldon Smith gets sacks. The 49ers love to stunt Aldon Smith around Justin Smith to the inside. Justin Smith is good at attacking the tackle-guard gap and holding the guard to prevent him from being able to pick up Aldon Smith when he stunts to the inside. It happened twice last week on Aldon Smith's sacks. On one of them, you can see it clearly on the tape. The other one is not as vivid, but a close look showed that Justin Smith did it both times. Here's a look at the one you can clearly see.

Aldon Smith is in the blue circle with Justin Smith in the yellow one. At the snap, Justin Smith attacks the guard-tackle gap, and Aldon Smith loops around. You can clearly tell Justin Smith is holding onto Rams left guard Shelley Smith to prevent him from having a chance to block Aldon Smith, who easily dumps Sam Bradford for a sack. This is something that never gets called, and Justin Smith is a pro at it.

2. With all the hype about Doug Martin in Tampa Bay the past month, one of the things that has been overlooked is how well Josh Freeman is playing. He has never been better. That might not mean from a numbers standpoint, but Freeman has a command of the offense like he has never had before. His ability to keep his head up and read the field has improved greatly. He is much more patient in the pocket. His 15-yard touchdown pass to Tiquan Underwood last week is proof of that. Here's a look.

At the snap, Freeman's initial read is outside to his right where the Bucs have a three-man bunch formation -- with Underwood on the outside of the bunch in the red circle. Vincent Jackson and Dallas Clark (yellow circles) are the initial reads, but Clark is blanketed and Jackson has a double. Underwood (red circle) runs to the middle of the field, but linebacker Demorrio Williams, who has dropped into zone coverage, has him covered. So Underwood continues across the field and gets open and Freeman turns and fires a pass to him for an easy touchdown.

3. Is there a better defensive player in the league right now than the Broncos' Von Miller? And that includes J.J. Watt. In the past couple of weeks, Miller has made a strong case to be the NFL Defensive Player of the Year. He owned the Carolina Panthers last week. And he did so even after getting his right leg rolled onto early in the game on a pass rush. He left, but came back. The Panthers probably wish he hadn't. Miller was all over the field, and he made some really nice plays against the run. The first of his two sacks wasn't even on a rush. Miller dropped into zone coverage in the middle of the field and spied Cam Newton. But when he saw Newton start to move, he showed off his speed and dropped him for a 6-yard loss. It was his amazing effort and speed that was the key to corner Tony Carter's 40-yard interception return for a touchdown. I will show that play down below. But Miller also knifed through blockers all day in the run game. He is not merely a pass rusher, that's for sure. Watch out, Watt. You have somebody closing fast to win the Defensive Player of the Year.

Here's a look at the Carter pick, a ball Newton had no business throwing. As you can see Miller (yellow circle) is lined up on the right side of the formation. The Panthers chip Miller first with receiver Brandon LaFell (blue circle) and then try to block him with tight end Ben Hartsock (red circle) who lines up as a fullback. Miller beats him inside with a quick move. As Newton bootlegs to his right, there's Miller. So Newton reverses his field, but Miller chases him down and lunges at his feet. Newton trips, and as he does, he throws a soft pass that Carter picks off and easily takes into the end zone. It's a bad decision by Newton, but it's a great play by Miller.

4. Where has the Giants' Victor Cruz gone? In the past three games, Cruz has 10 catches for 116 yards and no touchdowns. So I studied his performance against the Bengals to get an idea of why he isn't as effective as he was early in the season. Here's what I saw: Bengals corner Leon Hall doing a heck of a job on Cruz in man coverage. Hall was all over him the entire game, often with safety help over the top, which helped Hall's ability to mirror Cruz's routes. He undercut him a bunch, and he was physical with him. Cruz had three catches for 26 yards. It was obvious that the Bengals wanted to make Cruz a priority in terms of taking him away from Eli Manning. Cruz did beat Hall down the middle of the field for what should have been a long touchdown pass, but he dropped it. Even on that play, the safety did a poor job of getting over. Cruz is facing what all good receivers get as they improve. It appears that teams think taking him away is the No. 1 priority for stopping the Giants. Credit Hall for a good game, and credit defensive coordinator Mike Zimmer for a good plan. It helped that the Bengals were able to get pressure with their four-man rush.

5. For weeks, we've been wondering what's wrong with Vikings quarterback Christian Ponder. One of the things I noticed on tape was his inability to make plays down the field -- or have them even called. That's because the Vikings lack a deep threat. For all his quickness, Percy Harvin isn't that. That's why the play of rookie Jarius Wright was so important last week in beating the Lions. Wright can fly. And on the Vikings' third offensive play, he put that speed on display. Lining up in the slot on the right side of the formation, Wright just ran right through the coverage for a big play. The Lions were in a Cover-2 scheme and he ran right through the middle of it and gathered in a 54-yard bomb to set up the game's first touchdown. His speed seemed to surprise safety Eric Coleman, who seemed flat-footed as Wright ran by him in the middle of the field. Later, Wright scored his first NFL touchdown when he used two good rub routes to get free in the flat for a 3-yard touchdown catch. He was lined up inside of in a three-man bunch. Chris Houston was the corner who had him in coverage, but he couldn't get around the traffic made by the Michael Jenkins and Wright gathered in the pass for an easy score. His speed helped make it possible.

6. The Bengals have had big problems at center this season. Kyle Cook went down in the opener for the season. They signed Jeff Faine as a free agent off the street, but he has been bad. So the past two games they have started rookie Trevor Robinson. He got dinged against Denver and left the game. He did start against the Giants last week and played well. He got push in the run game and did a solid job in pass protection. He did get bull-rushed on one pass play, but for the most part he was sound. With Robinson starting inside next to rookie guard Kevin Zeitler and second-year guard Clint Boling, the Bengals have the youngest inside three in the league in terms of starts. Zeitler is having a heck of a season and Robinson has a chance to be a good one -- once he gets a little stronger in his backside.

7. There has been a lot made of Michael Turner's inability to get into the end zone last week on a third-and-goal play from the 2 against the Saints. In fairness to Turner, the tape showed it wasn't his fault. The offensive line didn't get push on the left side and defensive end Will Smith blew up the play. Earlier in the game, on a third-and-1, Turner was dumped for no gain and the Falcons had to kick a field goal. On that play, safety Malcolm Jenkins was able to knife in off the edge and dump Turner. He was unblocked, and Turner had no chance. But even so, I still think the Falcons need to get away from simply handing off to Turner in those situations. He is too slow to the line of scrimmage. It's time to use Jacquizz Rodgers more -- even in short-yardage situations.

8. I love the anatomy of a big play, which is exactly what Chris Ivory's 56-yard touchdown run was against the Falcons last week. Ivory, the Saints' backup running back, turned what should have been a short gain into a great run. The Falcons were in a 3-4 scheme at the time, with John Abraham standing up as an outside linebacker on the right side of the offensive formation. At the snap, Ivory took a step to the left, which pulled Abraham inside for a minute, which allowed tight end David Thomas to get a good enough block to hold him from getting to his outside contain. Once Ivory got around him, there were no linebackers because the Falcons were blitzing the right side of their defense. The only player left out there to make a tackle was corner Asante Samuel, and he took a bad angle to the inside and Ivory ducked around him. That left safety Thomas DeCoud -- who was single high -- to come over and make the tackle on the sideline. But he whiffed as Ivory cut it back inside. At about the 12-yard line, across the field, Falcons corner Dunta Robinson had one last chance to bring Ivory down, but he was the victim of a good stiff arm and all he could do was watch Ivory trot into the end zone. It was a great call against the right defense, but it also was a horrible display of tackling and angles by the Atlanta defense.

9. The Patriots are doing a nice thing by using outside rusher Jermaine Cunningham inside on passing downs. He hasn't lived up to expectations as an outside rusher, but he has done some nice things inside. He had a bull rush on Bills center Eric Wood last week to overpower him and get a sack of Ryan Fitzpatrick. He also had a nice pressure on an earlier play where Vince Wilfork got a sack and a forced a fumble. The Patriots have to get more pressure, and Cunningham's inside rush could be something that helps amp up that pass rush.

10. For weeks, we've heard a lot of praise for Giants safety Stevie Brown. But when the Bengals hit A.J. Green for a 58-yard touchdown pass on the first series of Cincinnati's win last week, Brown made a play so bad that two players were wide open. In addition to Green, tight end Jermaine Gresham was wide open in the middle of the field for what could have been a TD throw to him. Andy Dalton chose instead to throw to Green on the outside. On the play, the Bengals showed run-action to the left and Brown reacted and came up. By the time he realized it was a pass, it was too late. He was frozen in Nowhere Land. The pass went way over his head to Green for an easy score. Later on a 19-yard throw from Dalton to tight end Orson Charles, Brown got caught flat-footed in zone coverage and Charles ran right by him across the field to make the catch. Stevie Brown has done a nice job, but let's slow down on the praise for now.

Hot tub

1. Broncos QB Peyton Manning:He is playing out of his mind. Injury? What injury?

2. Seahawks CB Richard Sherman:He has a weekly spot here, it seems. Watching him against the Jets was a corner clinic.

3. Rams DE Chris Long: He ate up a good left tackle in Anthony Davis last week, and when the 49ers tried to block him with a tight end, he ate that up, too.

4. Chiefs OLB Justin Houston:He is an explosive player who is getting better each week.

5. Bucs LB Lavonte David:He continues to pile up tackles and covers a ton of ground. He is the best rookie defender in the league.

Cold tub

1. Dolphins QB Ryan Tannehill:Hey, rookie quarterbacks usually have games like that. He was terrible.

2. Jets QB Mark Sanchez:How does he make that throw that was picked off in the end zone? He has regressed.

Pete Prisco has covered the NFL for three decades, including working as a beat reporter in Jacksonville for the Jaguars. He hosted his own radio show for seven years, and is the self-anointed star of CBS Sports' show, Eye on Football. When he's not watching game tape, you can find Pete on Twitter or dreaming of an Arizona State national title in football.